Conventionally, a known vibration insulating member is employed to reduce propagation of vibration from one component to another component. Patent Document 1 discloses a vibration insulating member having a through hole. In the configuration of Patent Document 1, a shaft portion of a bolt is inserted in the through hole to connect one component with another component. The vibration insulating member has an inner wall forming the through hole, and the inner wall has a thread groove. The shaft portion of the bolt has an outer wall having a thread groove. The thread groove of the bolt is meshed with the thread groove of the through hole. Patent Document 2 discloses a vibration insulating member having a through hole in which a bolt is inserted to connect one component to another component. In Patent Document 2, the through hole has an inner diameter, which is greater than an outer diameter of a shaft portion of the bolt.
(Patent Document 1)
Publication of unexamined Japanese patent application No. 2008-286246
(Patent Document 2)
Publication of unexamined Japanese patent application No. H10 -318331
It is noted that, the vibration insulating member disclosed in Patent Document 1 may require additional manufacturing work to form the thread groove in the inner wall of the through hole. Therefore, the configuration of Patent Document 1 may incur increase in manufacturing cost of the vibration insulating member. It is further noted that, the vibration insulating member disclosed in Patent Document 2 may require hard manufacturing work to position the axis of the shaft portion relative to the bolt and the axis of the through hole. In addition, a contact state between the bolt and the vibration insulating member may vary in dependent upon the relative position between the bolt and the vibration insulating member. Therefore, the configuration of Patent Document 2 may not enable to reduce vibration propagation steadily.